JP4448897B2 - Photomask protective adhesive tape - Google Patents

Description

  The present invention relates to a photomask protecting adhesive tape that protects a photomask used in a printed circuit board formation process, and more specifically, it can be used without degrading the peeling effect even if adhesive exposure is repeated on an adhesive photoresist. It has excellent moldability and solvent resistance that prevents the surface protective layer from falling off even when a solvent such as alcohol is used for cleaning contaminant deposits from the resist. The present invention relates to an adhesive tape for protecting a photomask.

When producing a printed wiring board, an adhesive photoresist such as a liquid solder resist is used in order to exhibit functionality. For the purpose of protecting from the dirt and damage of the surface of the photomask for exposure used in close contact with such an adhesive photoresist, a photomask protective adhesive tape made of a polyester base material has been used conventionally. Yes. However, since the liquid solder resist has adhesiveness, there is a problem in that it is difficult to remove the photomask from the resist after exposure because the photoresist adheres to the surface of the photomask protecting adhesive tape.
In order to solve such problems, Patent Document 1 discloses that a release layer is coated on the surface of an adhesive tape for protecting a photomask. However, the release of the release agent is caused by repeating the contact exposure, and it is difficult to maintain the release effect.
Furthermore, the release layer is gradually eroded by the solvent contained in the photoresist as the adherend, the initiator decomposition product during UV curing, etc., and the release layer falls off and is sufficient for the photoresist. It has become a problem because the releasability cannot be sustained.

  In addition, the photomask protective adhesive tape with a release agent layer maintains the release effect because the release layer drops off when the contaminants attached to the surface are washed with a solvent such as alcohol due to insufficient adhesion of the release layer. Inability to do so was also a problem.

  In addition, when the photomask protective adhesive tape is transferred to the photomask in the field, or when the photomask protective adhesive tape bonded to the photomask is handled, there is a problem that the surface is slippery and difficult to handle. . In particular, this problem is not a fully automated line, but a particularly serious problem at a site where a person is working with a manual exposure machine or the like.

In order to solve this problem, in Patent Document 2, fine particles which are silica components called “organic inorganic hybrid resins” are blended in a surface protective layer made of silicone acrylate to suppress slipperiness by providing irregularities on the surface. An adhesive tape for protecting a photomask is mentioned.
However, in the surface protective film according to Patent Document 2, although slippage suppression and durability are surely measured at a stage where the number of exposures is low, stress due to contact with the photoresist increases as the number of exposures increases. By concentrating on the fine particle portion, the silica fine particles fall off, the removability is lowered, and the dropped fine particles become foreign matters. Furthermore, since fine particles are blended and provided with irregularities, transparency and HAZE are low from the initial stage, and pattern resolution and pattern reproducibility are low. Here, HAZE is a value measured according to JIS K7136 as in the following equation.
HAZE = diffuse transmittance / total light transmittance × 100

  In other words, in particular, in recent years, the adhesive tape for protecting a photomask has both releasability for repeated use of a photomask, and both releasability and durability against solvents such as alcohol as the number of exposures increases. And re-peelability (performance that does not leave glue on the adherend when peeled), antistatic property, durability of the release layer, and light transmission (transparency, high Those satisfying various performances such as HAZE) have been demanded.

JP 2003-96409 A JP 2005-181565 A

  The object of the present invention is an adhesive tape that protects the surface of an exposure photomask used in a printed circuit board formation process, and can be used without being reduced even if the adhesive exposure is repeated on an adhesive photoresist. It has excellent moldability and solvent resistance that prevents the surface protective layer from falling off even when a solvent such as alcohol is used for cleaning contaminant deposits from the resist. The present invention relates to an adhesive tape for protecting a photomask.

  In order to achieve the above-mentioned object, the present inventors have conducted extensive research, and as a result, are composed of a surface protective layer formed from a specific mixture or an intermediate layer and a surface layer formed sequentially from a specific mixture, respectively. The surface protective layer becomes a surface protective layer having both releasability and solvent resistance at the same time, and the photomask-protective adhesive tape using the surface protective layer maintains a light releasability with respect to the resist in the repeated steps of contact exposure. In addition to excellent releasability, the surface protective layer does not fall off even when washed with a solvent such as alcohol. Therefore, the release effect does not deteriorate, and the durability during repeated exposure and use is also good. It has been found that it becomes an adhesive tape. These findings have been further studied and the present invention has been completed.

That is, according to the first invention of the present invention, the transparent base film or sheet (A), the pressure-sensitive adhesive layer (B) formed on one surface thereof, and the surface of the pressure-sensitive adhesive layer (B) are opposite. A pressure-sensitive adhesive tape for photomask protection comprising a surface protective layer (C) formed on the side surface,
The surface protective layer (C) consists of a cured product obtained from a mixture containing the following (x), (y) and (z1) and / or (z2), and
In the mixture, the ratio of (x) and (y) is 5 to 30 parts by weight with respect to 100 parts by weight of (z1) and / or (z2). Provided.
(X): Isocyanatosilane (y): Siloxane having a hydroxyl group at the terminal (z1): Melamine compound (z2): Guanamin compound

Moreover, according to 2nd invention of this invention, a transparent base film or sheet | seat (A), the adhesive layer (B) formed in the single side | surface, and the surface of an adhesive layer (B) are opposite A pressure-sensitive adhesive tape for photomask protection comprising a surface protective layer (C) formed on the side surface,
The surface protective layer (C) is composed of an intermediate layer (d) and a surface layer (e) that are sequentially formed on the surface opposite to the surface of the pressure-sensitive adhesive layer (B),
The intermediate layer (d) is composed of a cured product containing a melamine compound (z1) and / or a guanamine compound (z2),
The surface layer (e) is composed of a cured product obtained from a mixture containing the following (x) and (y), and
The thickness of the surface layer (e) is 0.5 to 30% with respect to the thickness of the intermediate layer (d), and a photomask protecting adhesive tape is provided.
(X): Isocyanatosilane (y): Siloxane having a hydroxyl group at the terminal

  According to the third invention of the present invention, in the first or second invention, the surface protective layer (C) has a dynamic friction coefficient measured in accordance with JIS K7125 of 0.1 to 0.4. An adhesive tape for protecting a photomask is provided.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the isocyanate silane (x) is a tri- or tetrafunctional isocyanate silane. Is provided.

  According to a fifth aspect of the present invention, there is provided the pressure-sensitive adhesive tape for photomask protection according to the fourth aspect, wherein the tri- or tetrafunctional isocyanate silane is methyl triisocyanate silane or tetraisocyanate silane. Provided.

  According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the siloxane having a hydroxyl group at the terminal is a diol having two hydroxyl groups at the terminal. An adhesive tape for protecting a photomask is provided.

  According to the seventh invention of the present invention, in any one of the first to sixth inventions, the melamine compound (z1) is methylolmelamine or a derivative thereof. Is provided.

  According to an eighth aspect of the present invention, there is provided an adhesive tape for photomask protection according to the seventh aspect, wherein the methylol melamine is hexamethylol melamine.

  According to a ninth invention of the present invention, there is provided the photomask protecting adhesive tape according to any one of the first to eighth inventions, wherein the guanamine compound (z2) is benzoguanamine or a derivative thereof. Provided.

  According to the pressure-sensitive adhesive tape for protecting a photomask of the present invention, in the first invention, the surface protective layer (C) contains (x), (y) and (z1) and / or (z2) at a specific ratio. It is a pressure-sensitive adhesive tape for photomask protection that has a surface protective layer that has both mold release and solvent resistance at the same time by being formed from a specific mixture that contains it. In addition to maintaining removability and excellent removability, the release layer does not fall off even when washed with a solvent such as alcohol, so the release effect does not deteriorate, and durability during repeated exposure and use is also good. There is an effect that it is an adhesive tape for protecting a photomask, and a printed wiring board can be obtained by an efficient and economical method.

  In the second invention, the surface protective layer (C) is a combination of a specific layer composed of the intermediate layer (d) and the surface layer (e) with a specific thickness. It is an adhesive tape for photomask protection that has a surface protective layer that also has solvent resistance. At the same time, it is possible to maintain light releasability with respect to the resist and repeat removability in the repeated steps of contact exposure, and also with a solvent such as alcohol. Even if washed, the release layer does not fall off. Therefore, the release effect is not lowered, and it has the effect of being an adhesive tape for photomask protection that has good durability during repeated exposure and use. A printed wiring board can be obtained by an excellent method.

  In the third invention, since the surface protective layer (C) is specified to have a dynamic friction coefficient measured in accordance with JIS K7125 of 0.1 or more and 0.4 or less, the slip property is improved. The effect is that it is easy to work.

  In the fourth invention, since the isocyanate silane (x) is specified to be a tri- or tetrafunctional isocyanate silane, there is an effect that the performance of crosslinking a siloxane having a hydroxyl group at the terminal is excellent.

  In the fifth invention, since the tri- or tetrafunctional isocyanate silane is specified as methyl triisocyanate silane and / or tetraisocyanate silane, the ability to crosslink a siloxane having a hydroxyl group at the terminal is further improved. There is an effect.

  In the sixth invention, since the siloxane (y) having a hydroxyl group at the terminal is specified as a diol having two hydroxyl groups at the terminal, there is an effect that the crosslinking reactivity with isocyanate is excellent.

  In the seventh invention, since the melamine compound (z1) is specified to be methylolmelamine or a derivative thereof, the surface protective layer (C) or the intermediate layer (d) is a base film or sheet. There exists an effect that it is excellent in adhesiveness with PET used as (A).

  In the eighth invention, since the methylol melamine is specified as hexamethylol melamine, in the curable mixture that is the raw material of the surface protective layer (C) or the intermediate layer (d), There is an effect that it is excellent.

  In the ninth invention, since the guanamine compound (z2) is specified to be benzoguanamine or a derivative thereof, the surface protective layer (C) or the intermediate layer (d) is a base film or sheet ( There exists an effect that it is excellent in adhesiveness with PET used as A).

FIG. 1 is a schematic cross-sectional view showing the structure of an example of the photomask protecting adhesive tape of the present invention. (Examples 1 to 5, Comparative Examples 1 and 2) FIG. 2 is a schematic cross-sectional view showing a configuration of an example of the photomask protecting adhesive tape of the present invention. (Examples 6 to 9, Comparative Examples 5 and 6) FIG. 3 is a graph showing the relationship between the blending ratio of methyl isocyanate and diol siloxane to the melamine resin of the surface protective layer (C) of the present invention, the dynamic friction coefficient, and the peeling force. FIG. 4 is a graph showing the relationship between the value of the surface layer (d) / intermediate layer (e) of the surface protective layer (C) of the present invention, the dynamic friction coefficient, and the peeling force.

Explanation of symbols

A Transparent base film or sheet B Adhesive layer C Surface protective layer e Surface layer d Intermediate layer

Hereinafter, the adhesive tape for protecting a photomask of the present invention will be described in detail.
The pressure-sensitive adhesive tape for protecting a photomask of the present invention comprises a transparent substrate film or sheet (A), an adhesive layer (B) formed on one side thereof, and an adhesive for the substrate film or sheet (A). A surface protective layer (C) made of a cured product obtained from a specific mixture, formed on a surface opposite to the surface on which the layer (B) is provided, and in the mixture, (x) and ratio of (y) is a photomask protecting adhesive tape, which is a (z 1) and / or (z2) with respect to 100 parts by weight, 5-30 parts by weight.
Moreover, the adhesive tape for photomask protection of this invention is opposite to the surface of a transparent base film or sheet (A), the adhesive layer (B) formed in the single side | surface, and an adhesive layer (B). A surface protective layer (C) formed of two layers of a specific intermediate layer (d) and a surface layer (e), respectively, formed on the side surface, and the thickness of the surface layer (e) is A pressure-sensitive adhesive tape for protecting a photomask, wherein the pressure-sensitive adhesive tape is 0.5% to 30% with respect to the thickness of the intermediate layer (d).

1. Base film or sheet (A)
The base film or sheet (A) is not particularly limited as long as it has a high transmittance of ultraviolet rays used in exposure. For example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polypropylene, polyethylene, poly A polymer film having excellent transparency made of a resin such as vinyl chloride, polystyrene, polycarbonate, triacetyl cellulose (TAC), polyimide, or acrylic is preferably used. In particular, a biaxially stretched PET film is preferably used because of its excellent mechanical strength and dimensional stability.

  The thickness of the base film or sheet (A) is preferably appropriately determined in consideration of light transmittance, handleability, and the like. Specifically, the thickness is preferably 2 to 100 μm, and more preferably 4 ˜25 μm. If the thickness is less than 2 μm, the strength of the tape may be insufficient and handling may be difficult, and wrinkling may occur when the tape is applied. If the thickness exceeds 100 μm, sufficient light transmission may not be obtained.

Moreover, in this invention, in order to improve the adhesiveness of a transparent base film or sheet (A), a surface protective layer (C) or an intermediate | middle layer (d), and an adhesive layer (B), surface treatment is performed. Can do.
For example, there are discharge treatments such as corona treatment and plasma treatment. In order to perform uniform treatment on a thin base material, a weak discharge with low processing energy is desirable to prevent problems such as base material breakage and perforation. As another method, saponification treatment with alkali is known.

2. Surface protective layer (C)
The surface protective layer (C) of the present invention is formed from a curable mixture containing isocyanate silane (x), siloxane (y) having a hydroxyl group at the terminal, and a melamine compound (z1) and / or a guanamine compound (z2). And the ratio of (x) and (y) is 0.5 to 30 parts by weight with respect to 100 parts by weight of (z1) and / or (z2) in the mixture. To do.
The surface protective layer (C) of the present invention comprises two layers of a specific intermediate layer (d) and a surface layer (e), and the thickness of the surface layer (e) is the intermediate layer (d). It is characterized by being 0.5% or more and 30% or less with respect to the thickness of

  The surface protective layer (C) is provided on a transparent substrate film or sheet (A), and the surface protective layer (C) is adhered to the surface of the photoresist, so that the photoresist It acts as a release layer that prevents transfer from being transferred to the mask protecting adhesive tape.

In general, it is known that compounds such as silicone and fluorine come out selectively on the surface and line up on the surface even when mixed with other compounds and solvents because of their low critical surface tension. In the present invention, an adhesive tape for protecting a photomask having both slip resistance and durability is provided by controlling the amount of silicone on the surface layer by utilizing the properties of compounds such as silicone and fluorine.
This is because the two components of the first invention of the present invention are made into one component (hereinafter also referred to as “one component mixing type”), and the two components of the second invention of the present invention are separately coated in two layers. The effect can also be obtained by controlling the silicone amount of the silicone layer in the outermost layer (surface layer (e)).
Further, in the case of the two-layer coating, after the intermediate layer (d) is applied, the surface layer silicone is applied in a lattice shape (JP 2007-154144, etc.) or a dot shape (JP 2007-154168, etc.). Effects can be obtained. When this method is applied to the use of the present invention, it can be expected that the effect of blending fine particles, which will be described later, becomes the starting point of peeling at the silicone part of the surface layer (surface layer (e)).

The surface protective layer (C) of the present invention preferably has a dynamic friction coefficient measured in accordance with JIS K7125 of 0.1 or more and 0.4 or less. Thereby, the ease of work by improving the slipperiness is first mentioned as an effect.
This is an effect achieved by controlling the amount of silicone on the surface of the surface protective layer, and the slip property can be expressed by a dynamic friction coefficient. The dynamic friction coefficient is preferably 0.1 or more and 0.4 or less, More preferably, it is 0.15 or more and 0.35 or less.

(1) When the surface protective layer (C) is a single layer (i) Curable mixture (x): Isocyanate silane The crosslinking agent isocyanate silane (x) used in the surface protective layer (C) of the present invention is Si ( _{NCO) 4, R n Si (} NCO) 4-n, there is a _4-n, etc. _{(RO) n Si (NCO)} . Here, R is a hydrocarbon group, and n is a number of 1, 2 or 3.
Among such compounds, tri- or tetrafunctional isocyanate silanes such as methyl triisocyanate silane and tetraisocyanate silane are preferable from the viewpoint of reactivity. The isocyanate silane can be used alone or in a mixture of two or more.

(Y): Siloxane having a hydroxyl group at the terminal Examples of the siloxane (y) having a terminal hydroxyl group used in the surface protective layer (C) of the present invention include silanol-modified and carbinol-modified dimethylpolysiloxane. From the viewpoint of a crosslinking reaction with isocyanate, a diol having two hydroxyl groups is preferable.

The isocyanate silane used in the present invention acts as a crosslinking agent for siloxane containing a hydroxyl group at the terminal. As a crosslinking reaction mechanism between a siloxane having a hydroxyl group at the terminal and an isocyanate silane that is a crosslinking agent thereof,
1) Isocyanate silane applied to a transparent substrate film or sheet (A) reacts with moisture in the air in the drying stage to hydrolyze and form silanol groups Si-NCO + H ₂ O → Si-OH + HNCO
2) Cross-linked by dehydration condensation reaction between the formed silanol and the hydroxyl group of siloxane Si-OH + Si-OH → Si-O-Si + H ₂ O
3) Reaction with siloxane containing a hydroxyl group at the end simultaneously Si—OH + HO—Si (CH ₃ ) ₂ —O˜ → Si—O—Si (CH ₃ ) ₂ —O˜ + H ₂ O
4) It is considered that the water produced in 2) and 3) is supplied to the isocyanate silane and the crosslinking reaction proceeds.
It is considered that the isocyanate group becomes HNCO by the cross-linking reaction and reacts with water to generate carbon dioxide and ammonia, so that it is discharged out of the reaction system.
HNCO + H ₂ O → NH ₃ + CO ₂

The surface protective layer (C) of the present invention thus obtained has releasability and solvent resistance, so that it does not fall off even when washed with a solvent such as alcohol, and the demolding effect does not deteriorate, Durability during repeated exposure and use is also good.
Therefore, it can be suitably used as a surface protective layer of a photomask protecting adhesive tape for protecting the surface of an exposure photomask used in close contact with an adhesive photoresist in a printed circuit board forming step.

(Z1): Melamine compound As the melamine compound (z1) used in the present invention, methylolated melamine obtained by reacting melamine with formaldehyde, for example, monomethylolmelamine to hexamethylolmelamine, or an alkyl ether of a derivative thereof A chemical compound. Among these, hexamethylol melamine has many OH groups and is desirable from the viewpoint of adhesion to PET.
Melamine compounds may be used alone or in combination of two or more.
Due to the compounding of the melamine-based compound, the adhesion with the transparent base film (A) is improved, and the surface protective layer (C) is difficult to fall off when washing with a solvent such as alcohol without using an undercoat layer. There is a feature.

(Z2): Guanamine compound As the guanamine compound (z2) used in the present invention, benzoguanamine, acetoguanamine, cyclohexanecarboguanamine, cyclohexenecarboguanamine, norbornenecarboguanamine, and derivatives thereof are methylolated guanamine or alkyl etherification. The body is mentioned.
Of the cured products containing a guanamine compound, a cured product using benzoguanamine and its derivative is particularly preferable because it has good adhesion to PET and the surface layer (C) used as a film or sheet (A).
A guanamine type compound may be used independently or may be used in combination of 2 or more types.
By blending the guanamine-based compound, the adhesion with the transparent base film (A) is improved, and the surface layer (C) is less likely to fall off when washed with a solvent such as alcohol without using an undercoat layer. There are features.

(Ii) Compounding ratio The compounding ratio of the isocyanate silane (x) and the siloxane (y) having a hydroxyl group at the terminal is 5 to 200 parts by weight of siloxane with respect to 100 parts by weight of isocyanate silane, preferably 10 to 100 parts by weight. Preferably it is 10-50 weight part. When the amount is 5 parts by weight or less, the expression of releasability is alienated, and when it is 200 parts by weight or more, the adhesion to the base film or sheet (A) may be lowered.
The mixing ratio when the melamine compound (z1) and / or the guanamine compound (z2) is mixed with the surface protective layer (C) is 100 weights of the melamine compound (z1) and / or the guanamine compound (z2). The proportion of isocyanate silane (x) and siloxane (y) having a hydroxyl group at the terminal is 0.5 to 30 parts by weight, preferably 5 to 25 parts by weight, and more preferably 10 to 20 parts by weight with respect to parts. If it is 0.5 parts by weight or less, the amount of silicone is insufficient, and the slipperiness can be improved, but the durability is lowered. If it is 30 parts by weight or more, the durability is good, but the slipperiness cannot be improved.

(Iii) Thickness When the surface protective layer (C) is one layer, the thickness of the surface protective layer (C) is 0.01 to 2 μm for reasons such as coating uniformity, curability and adhesion. Is more preferable, and more preferably 0.02 to 0.5 μm. When the thickness is less than 0.01 μm, it is difficult to apply uniformly, and there is a possibility that the releasability may vary, and when it exceeds 2 μm, there is a possibility that curing failure or falling off easily occurs.

(Iv) Production of surface protective layer (C) The surface protective layer (C) of the present invention is formed on one surface of a transparent substrate film or sheet (A), and is an isocyanate silane (x) and a siloxane having a hydroxyl group at the terminal. A mixture of (y) or a mixture containing melamine compound (z1) and / or guanamine compound (z2) in addition to isocyanate silane (x) and siloxane (y) having a hydroxyl group at the terminal is diluted in an organic solvent. It is formed by obtaining a cured product obtained by heating and drying after coating. At that time, the order of blending the components is not particularly limited, and as a coating method, for example, spin coating, spray coating, roll coating such as gravure, die coating, or the like can be used.

(2) When the surface protective layer (C) has two layers When the surface protective layer (C) consists of two layers (intermediate layer (d) and surface layer (e)), in other words, a base film or sheet (A When the intermediate layer (d) is provided between the surface layer (e) and the surface layer (e), the intermediate layer (d) is prepared from a mixture containing the following melamine compound (z1) and / or guanamine compound (z2). It consists of the hardened | cured material obtained. At this time, the surface layer (e) is made of a cured product obtained from a mixture containing the following isocyanate silane (x) and siloxane (y) having a hydroxyl group at the terminal.

(I) Intermediate layer (d)
(Z1): Melamine compound As the melamine compound (z1) used in the intermediate layer (d) of the present invention, a methylolated melamine obtained by reacting melamine with formaldehyde, for example, hexamethylolmelamine from monomethylolmelamine, Or the alkyl etherified substance of the derivative is mentioned. Among these, hexamethylol melamine has many OH groups and is desirable from the viewpoint of adhesion to PET.
The melamine compound (z1) may be used alone or in combination of two or more.
By blending the melamine compound (z1), adhesion with the transparent base film (A) can be improved, and the surface protective layer (C) can be used for cleaning with a solvent such as alcohol without using an undercoat layer. There is a feature that it is difficult to fall off or the intermediate layer (d) and the surface layer (e) are difficult to peel off.

(Z2): Guanamine compound As the guanamine compound (z2) used in the intermediate layer (d) of the present invention, benzoguanamine, acetoguanamine, cyclohexanecarboguanamine, cyclohexenecarboguanamine, norbornenecarboguanamine, and methylol of its derivative Guanamine or alkyl etherified compounds.
Of the cured products containing a guanamine compound, a cured product using benzoguanamine and its derivative is particularly preferable because it has good adhesion to PET and the surface layer (e) used as a film or sheet (A).
A guanamine type compound may be used independently or may be used in combination of 2 or more types.
Due to the compounding of the guanamine compound, the surface layer (e) is less likely to fall off when washed with a solvent such as alcohol without using an undercoat layer, etc. The intermediate layer (d) and the surface layer (e) are difficult to peel off.

  The blending ratio when the melamine compound (z1) and the guanamine compound (z2) are mixed and used is preferably 1: 1.

The intermediate layer (d) can contain other binder resins and the like within a range that does not inhibit the adhesion improving action by the melamine compound and / or the guanamine compound.
As the binder resin, a resin having excellent adhesiveness with the substrate can be selected according to the type of the substrate. Desirably, it is preferable to employ a resin curable with a melamine compound and / or a guanamine compound. Thus, by containing a melamine compound and / or a guanamine compound and a curable resin, the solvent resistance of the intermediate layer (d), the intermediate layer (d), the substrate (A) and / or the surface layer ( Adhesiveness with e) can be expressed.
Examples of resins that cure with melamine compounds and / or guanamine compounds include acrylic resins, alkyd resins, polyester resins, and silicone resins. For example, as a reaction with a methylolated guanamine compound, a silicone resin having a silanol group can be heated to undergo a condensation reaction and cured.

As the melamine compound and / or guanamine compound contained in 100 parts by weight of the intermediate layer (d), the base film or sheet (A) is contained by containing 5% by weight or more, more preferably 15% by weight or more. As a result, the adhesion with PET and / or the surface layer (e) can be improved. If it is less than 5% by weight, sufficient adhesion may not be obtained.
Melamine compounds and / or guanamine compounds may be used alone or in combination of two or more.

  As a method of forming a cured product layer containing a melamine compound and / or a guanamine compound as the intermediate layer (d), the mixture is diluted with an organic solvent on one side of the transparent substrate film or sheet (A) and applied. It can be obtained by heat drying. As a coating method, methods such as spin coating, spray coating, roll coating such as gravure, and die coating can be used.

(Ii) Surface layer (e)
(X): used for the surface layer of the isocyanate silane present invention (e), isocyanate silane crosslinking agent (x) is _{Si (NCO), R n Si} (NCO) 4-n, (RO) n Si (NCO) _4-n etc. Here, R is a hydrocarbon group, and n is a number of 1, 2 or 3.
Among such compounds, tri- or tetrafunctional isocyanate silanes such as methyl triisocyanate silane and tetraisocyanate silane are preferable from the viewpoint of reactivity. The isocyanate silane can be used alone or in a mixture of two or more.

(Y): Siloxane having a hydroxyl group at the terminal Examples of the siloxane (y) having a terminal hydroxyl group used in the surface layer (e) of the present invention include silanol-modified and carbinol-modified dimethylpolysiloxane. From the viewpoint of a crosslinking reaction with isocyanate, a diol having two hydroxyl groups is preferable.

The isocyanate silane used in the present invention acts as a crosslinking agent for siloxane containing a hydroxyl group at the terminal. As a crosslinking reaction mechanism between a siloxane having a hydroxyl group at the terminal and an isocyanate silane that is a crosslinking agent thereof,
1) The isocyanate silane applied to the intermediate layer (d) reacts with moisture in the air in the drying stage to hydrolyze and form silanol groups. Si-NCO + H ₂ O → Si—OH + HNCO
2) Cross-linked by dehydration condensation reaction between the formed silanol and the hydroxyl group of siloxane Si-OH + Si-OH → Si-O-Si + H ₂ O
3) Reaction with siloxane containing a hydroxyl group at the end simultaneously Si—OH + HO—Si (CH ₃ ) ₂ —O˜ → Si—O—Si (CH ₃ ) ₂ —O˜ + H ₂ O
4) It is considered that the water produced in 2) and 3) is supplied to the isocyanate silane and the crosslinking reaction proceeds.
It is considered that the isocyanate group becomes HNCO by the cross-linking reaction and reacts with water to generate carbon dioxide and ammonia, so that it is discharged out of the reaction system.
HNCO + H ₂ O → NH ₃ + CO ₂

The surface layer (e) of the present invention thus obtained has releasability and solvent resistance, so that it does not fall off even when washed with a solvent such as alcohol, and the releasability is not lowered. Durability during exposure and use is also good.
Therefore, it can be suitably used as a surface protective layer of a photomask protecting adhesive tape for protecting the surface of an exposure photomask used in close contact with an adhesive photoresist in a printed circuit board forming step.

  The compounding ratio of isocyanate silane (x) and siloxane (y) having a hydroxyl group at the terminal is 5 to 200 parts by weight of siloxane, preferably 10 to 100 parts by weight, more preferably 10 to 50 parts by weight based on 100 parts by weight of isocyanate silane. Parts by weight. If it is 5 parts by weight or less, the release property is alienated, and if it is 200 parts by weight or more, the adhesion to the base film or sheet (A) may be lowered.

(Iii) Thickness In the case of a two-layer coat (when an intermediate layer (d) is provided), the thickness of the surface layer (e) made of a cured product obtained from a mixture containing (x) and (y) is melamine-based It is necessary to be 0.5 % or more and 30% or less with respect to the thickness of the intermediate layer (d) made of the cured product containing the compound (z1) and / or the guanamine compound (z2). Also in the case of a two-layer coat, the ratio of (x) and (y) is preferably 5 to 50 parts by weight with respect to (z) 100 parts by weight.
Moreover, the thickness of the surface protective layer (C) which combines the intermediate layer (d) and the surface layer (e) is 0.01 to 2 μm for reasons such as coating uniformity, curability and adhesion. Is more preferable, and more preferably 0.02 to 0.5 μm. When the thickness is less than 0.01 μm, it is difficult to apply uniformly, and there is a possibility that the releasability may vary, and when it exceeds 2 μm, there is a possibility that curing failure or falling off easily occurs.

(Iv) Production of intermediate layer (d) and surface layer (e) The intermediate layer (d) of the present invention is formed on one surface of a transparent substrate film or sheet (A), and contains a melamine compound (z1) and / or Alternatively, it is formed by diluting a mixture containing a guanamine compound (z2) in an organic solvent, applying and drying by heating, and obtaining a cured product.
Further, the surface layer (e) of the present invention is formed on one surface of the intermediate layer (d), and is diluted with an organic solvent and coated with an isocyanate silane (x) and a siloxane (y) having a hydroxyl group at the terminal. It is formed by obtaining a cured product obtained by heating and drying.
At that time, the order of blending the components is not particularly limited, and as a coating method, for example, spin coating, spray coating, roll coating such as gravure, die coating, or the like can be used.

3. Adhesive layer (B)
The pressure-sensitive adhesive layer (B) used in the present invention is attached to the surface of an exposure original document that is a photomask, and is not particularly limited, but an acrylic pressure-sensitive adhesive is preferable in consideration of transparency. As the acrylic pressure-sensitive adhesive, those mainly composed of an acrylic polymer comprising a copolymer of a (meth) acrylic acid ester monomer and a functional group-containing monomer are preferable, and the polymerization method is not particularly limited.
Examples of (meth) acrylic acid esters include butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, and the like. Can be used together. Of these, butyl acrylate and -2-ethylhexyl acrylate are preferable from the viewpoint of low Tg and viscoelasticity.
Examples of the functional group-containing monomer include acrylic acid and methacrylic acid.
The acrylic pressure-sensitive adhesive preferably has a partially crosslinked structure inside the acrylic polymer. Since the cohesive force of the pressure-sensitive adhesive is enhanced by having a cross-linked structure, it is difficult for adhesive to remain when the tape is peeled off. Such a crosslinked structure can be formed by using a crosslinking agent capable of reacting with the functional group-containing monomer. As the crosslinking agent, for example, an epoxy crosslinking agent, an aliphatic or aromatic isocyanate-based crosslinking agent, and the like are preferable. Used for.
As a method of forming the pressure-sensitive adhesive layer (B), using a roll coater such as a gravure, a comma coater, a die coater or the like, a method of directly applying a pressure-sensitive adhesive to one side of a separator and drying, or once on a release paper The method of transferring to one side of a separator after providing an adhesive layer by the same method, etc. can be used.
The thickness of the pressure-sensitive adhesive layer (B) is preferably determined as appropriate depending on the adhesive strength and the like, but specifically, it is preferably 1 to 50 μm, and more preferably 2 to 25 μm.
If the thickness is less than 1 μm, the adhesive strength to the photomask may be insufficient, or bubbles may be involved in the photomask irregularities, while if it exceeds 50 μm, sufficient light transmission properties are obtained. May not be obtained, or when a scattered light source is used, pattern resolution may be reduced due to light scattering.

In the present invention, in order to improve the adhesive strength, a so-called tackifier resin (tackifier) component can be blended and used. A tackifier component, also called a tackifier, is a substance that is blended in an elastomer to improve the adhesive function, and is usually an amorphous oligomer with a molecular weight of several hundred to several thousand, which is a liquid or solid heat at room temperature. It is a plastic resin.
The type of tackifier is not particularly limited, such as natural resin typified by rosin resin, terpene resin, aliphatic, aromatic, copolymer petroleum resin, phenolic resin, xylene resin, etc. A synthetic resin system is exemplified. These may be used alone or in combination of two or more.
Since tackifiers normally inhibit light transmission, it is preferable to use a rosin resin and a terpene phenol resin in combination in order to achieve a suitable adhesive performance without increasing the haze value.
5-80 weight part is preferable with respect to 100 weight part of adhesive components, and, as for the compounding quantity of a tackifier component, it is more preferable that it is 8-50 weight part. If the amount of the tackifier is too small, the required adhesive strength cannot be obtained. If the amount is too large, the adhesive layer cannot be peeled off together with the substrate when re-peeling, that is, a problem of adhesive residue is likely to occur. In practice, it becomes difficult to use.

4). Other layers (1) Antistatic layer An antistatic layer or the like should be provided on the surface of the substrate opposite to the surface on which the pressure-sensitive adhesive layer (B) is provided, as long as it does not affect light transmission. Can do. The antistatic layer has a role of preventing the tape from being charged and attracting dust in the air.

The antistatic layer can be freely selected as long as the adhesion of the surface protective layer (C) is not impaired.
Antistatic agents include, for example, cationic antistatic agents such as quaternary ammonium salts and primary to tertiary amino groups, anionic antistatic agents such as sulfonate groups, nitrate ester bases, and phosphate ester bases, amino acid series These amphoteric antistatic agents, glycerin-based or polyethylene glycol-based nonionic antistatic agents, and the like may be used alone or in combination.
Moreover, what dispersed electroconductive fine particles in resin, such as an acryl, is mentioned. Although it does not specifically limit as said electroconductive fine particle, For example, antimony dope tin oxide fine particle etc. are preferable from being hard to affect a light transmittance.
An antistatic layer can be obtained by applying the above-mentioned antistatic agent to the surface of a plastic product or mixing it inside.

(2) Protective film layer Moreover, it is preferable that the protective layer is laminated | stacked in the outermost part at the side of an adhesive layer (B) in order to protect an adhesive layer and to make it easy to handle. The protective layer is not particularly limited, and examples thereof include a polyethylene terephthalate film on which a silicone release layer is formed. This protective layer is peeled off from the adhesive tape before the photomask protecting adhesive tape of the present invention is applied to the photomask. Although the thickness of a protective film is not specifically limited, Generally the thing of the range of 12-75 micrometers is used.

5). Photomask protective adhesive tape The photomask protective adhesive tape of the present invention comprises a transparent substrate film or sheet (A), an adhesive layer (B) formed on one side thereof, and an adhesive layer (B). And a surface protective layer (C) made of a cured product obtained from a specific mixture formed on the surface opposite to the surface, and in the mixture, the ratio of (x) and (y) is ( relative to z 1) and / or (z2) 100 parts by weight, and photomask protecting adhesive tape, characterized in that from 5 to 30 wt parts.
Moreover, the adhesive tape for photomask protection of this invention is opposite to the surface of a transparent base film or sheet (A), the adhesive layer (B) formed in the single side | surface, and an adhesive layer (B). A surface protective layer (C) formed of two layers of a specific intermediate layer (d) and a surface layer (e), respectively, formed on the side surface, and the thickness of the surface layer (e) is A pressure-sensitive adhesive tape for protecting a photomask, wherein the pressure-sensitive adhesive tape is 0.5% to 30% with respect to the thickness of the intermediate layer (d).
Furthermore, an antistatic layer, a protective layer, etc. can be provided as other layers.
Therefore, the photomask-protective pressure-sensitive adhesive tape of the present invention can maintain releasability from the resist in the repeated steps of contact exposure. In addition, when there is a contaminant deposit from the resist on the surface layer of the photomask protective adhesive tape, the photomask protective adhesive tape has the effect that the surface layer does not fall off even when washed with a solvent such as alcohol. It has the feature that a printed wiring board can be manufactured by a method that is excellent in terms of economy and economy.

  Hereinafter, the present invention will be described in more detail by way of examples and comparative examples of the present invention, but the present invention is not limited to these examples.

[Example 1]
An isocyanate cross-linked acrylic pressure-sensitive adhesive (“SK Dyne 1425” manufactured by Soken Chemical Co., Ltd.) is toluene on a 25 μm-thick separator (“PET 2511” manufactured by Lintec Co., Ltd.) having a silicone release agent layer formed on one side of the PET substrate. Was diluted to a solid content concentration of 10% by weight, and after coating, dried at 120 ° C. for 30 seconds to provide a pressure-sensitive adhesive layer having a thickness of 5 μm after drying. Subsequently, the pressure-sensitive adhesive layer was laminated with a 6 μm thick biaxially stretched transparent PET base film (“F53 # 6C” manufactured by Toray Industries, Inc.) to prepare an adhesive tape.
Next, the transparent PET base material surface of the above-mentioned adhesive tape was subjected to corona treatment so as not to repel “Wet tension test mixed solution No 48.0” manufactured by Wako Pure Chemical Industries, Ltd., and then a methylol group as a melamine compound. 100 parts by weight of methylated melamine resin (“Cymel 370” manufactured by Mitsui Cytec Co., Ltd.), 4 parts by weight of methyl triisocyanate (“SI-310” manufactured by Matsumoto Pharmaceutical Co., Ltd.) and diol siloxane (“KF-9701” manufactured by Shin-Etsu Chemical Co., Ltd.) 1 Dilute 5 parts by weight of the mixture with MEK to a solid content concentration of 5% by weight, dry at 130 ° C. for 120 seconds, and provide a dried surface coating layer having a thickness of 0.1 μm. It was created.

[Examples 2 to 5, Comparative Examples 1 and 2]
A pressure-sensitive adhesive tape for photomask protection was prepared in the same manner as in Example 1 except that the compounding ratio of methylol-based methylated melamine resin and methyltriisocyanate and diolsiloxane was changed to that shown in Table 1. Created.

[Comparative Example 3]
An isocyanate cross-linked acrylic pressure-sensitive adhesive (“SK Dyne 1425” manufactured by Soken Chemical Co., Ltd.) is added to toluene on a 25 μm thick separator (“2511” manufactured by Lintec Co., Ltd.) having a silicone release agent layer formed on one side of a PET substrate. Was diluted to a solid content concentration of 10% by weight, and after coating, dried at 120 ° C. for 30 seconds to provide a pressure-sensitive adhesive layer having a thickness of 5 μm after drying. Subsequently, the pressure-sensitive adhesive layer was laminated with a 6 μm thick biaxially stretched transparent PET base film (“F53 # 6C” manufactured by Toray Industries, Inc.) to prepare an adhesive tape.
Next, the surface of the transparent PET base material of the adhesive tape was subjected to corona treatment so as not to be repelled by “Wet tension test mixed solution No 48.0” manufactured by Wako Pure Chemical Industries, Ltd., and then KS-847T ( 0.2 parts by weight of platinum-based catalyst CAT-PL-50T (manufactured by Shin-Etsu Chemical) and 2.5 of X-92-185 (manufactured by Shin-Etsu Chemical) as an adhesion improver for 100 parts by weight of Shin-Etsu Chemical) A part by weight of the mixture was diluted with toluene to a solid content concentration of 3% by weight, and after coating, dried at 110 ° C. for 120 seconds to obtain a silicone resin layer having a thickness of 0.1 μm.

[Comparative Example 4]
An isocyanate cross-linked acrylic pressure-sensitive adhesive (“SK Dyne 1425” manufactured by Soken Chemical Co., Ltd.) is added to toluene on a 25 μm thick separator (“2511” manufactured by Lintec Co., Ltd.) having a silicone release agent layer formed on one side of a PET substrate. Was diluted to a solid content concentration of 10% by weight, and after coating, dried at 120 ° C. for 30 seconds to provide a pressure-sensitive adhesive layer having a thickness of 5 μm after drying. Subsequently, the pressure-sensitive adhesive layer was laminated with a 6 μm thick biaxially stretched transparent PET base film (“F53 # 6C” manufactured by Toray Industries, Inc.) to prepare an adhesive tape.
Next, the surface of the transparent PET base material of the adhesive tape was subjected to corona treatment so that “wetting tension test mixed solution No 48.0” manufactured by Wako Pure Chemical Industries, Ltd. was not repelled. On the upper surface, 80 parts by weight of addition reaction type silicone (“LTC750A” manufactured by Toray Dow Corning), 0.8 part by weight of a platinum catalyst (“SRS212” manufactured by Toray Dow Corning), and a silane coupling agent (γ-Gly Silica having an average particle size of 30 nm as a fine particle (“R972” manufactured by Nippon Aerosil Co., Ltd.) with respect to 100 parts by weight of the solid content of the surface layer containing 1 part by weight of Sidoxypropyltrimethoxysilane (“TSL8350” manufactured by Momentive Materials Japan) 5 parts by weight was mixed, diluted with toluene to a solid content concentration of 3% by weight, coated and then dried at 110 ° C. for 120 seconds to prepare a photomask protecting pressure-sensitive adhesive tape having a thickness of 0.2 μm after drying. .

[Example 6]
An isocyanate cross-linked acrylic pressure-sensitive adhesive (“SK Dyne 1425” manufactured by Soken Chemical Co., Ltd.) is added to toluene on a 25 μm thick separator (“2511” manufactured by Lintec Co., Ltd.) having a silicone release agent layer formed on one side of a PET substrate. Was diluted to a solid content concentration of 10% by weight, and after coating, dried at 120 ° C. for 30 seconds to provide a pressure-sensitive adhesive layer having a thickness of 5 μm after drying. Subsequently, the pressure-sensitive adhesive layer was laminated with a 6 μm thick biaxially stretched transparent PET base film (“F53 # 6C” manufactured by Toray Industries, Inc.) to prepare an adhesive tape.
Next, the surface of the transparent PET base material of the adhesive tape was subjected to corona treatment so as not to be repelled by “Wet tension test mixed solution No 48.0” manufactured by Wako Pure Chemical Industries, Ltd., and then methylol-based methyl as a melamine resin. Melamine resin (“Cymel 370” manufactured by Mitsui Cytec Co., Ltd.) diluted with MEK to a solid content concentration of 5% by weight, dried at 130 ° C. for 120 seconds and dried to a thickness of 0.1 μm from the melamine resin An intermediate layer was obtained.
A mixture of 80 parts by weight of methyl triisocyanate (“SI-310” manufactured by Matsumoto Pharmaceutical Co., Ltd.) and 20 parts by weight of diol siloxane (“KF-9701” manufactured by Shin-Etsu Chemical Co., Ltd.) on the upper surface of the intermediate layer was 2% by weight with ethyl acetate. After diluting to a solid content concentration and coating, drying was performed at 110 ° C. for 120 seconds, and a surface layer having a thickness of 0.02 μm after drying was provided to prepare an adhesive tape for photomask protection.
In this example, the thickness of the cured product of the mixture containing methyl triisocyanate and diol siloxane was 20% of the thickness of the cured product of the methylol group-type methylated melamine resin.

[Examples 7 to 9, Comparative Examples 5 and 6]
As in Example 7, except that the thickness of the mixture containing methyl triisocyanate and diol siloxane with respect to 0.1 μm of the methylol group-type methylated melamine resin as the melamine compound was changed to that shown in Table 2. An adhesive tape for photomask protection was prepared. In Comparative Example 5, a surface layer made of a mixture containing methyl triisocyanate and diol siloxane was not provided.

[Evaluation]
About the adhesive tape for photomask protection obtained by the Example and the comparative example, it evaluated by the following method.

(1) Ethanol wear test:
A 200 g weight wrapped with absorbent cotton dampened with 1 g of ethanol was placed on the release agent-coated surface of the photomask protecting adhesive tape and reciprocated 50 and 100 times. An acrylic pressure-sensitive adhesive tape (“# 31B” manufactured by Nitto Denko Corporation) was pressed and bonded to the test surface with a 2 kg roller to prepare an evaluation sample. About this evaluation sample, the 180 degree peeling test of the adhesive tape for photomask protection was performed at a peeling speed of 300 mm / min, and the peeling strength was measured. Those having a small increase in peel strength compared to the initial value are good.

(2) Adhesion exposure test:
Photoresist protective tape (photo ink ("IPL175SHG" manufactured by Fuji Photo Film Co., Ltd.)) is attached to a photomask, and a glass epoxy patterned 1 mm thick substrate is used to make a photoresist (solar ink) by a screen printer. AUS308) was applied and a test substrate was prepared so that the film thickness after drying at 80 ° C. for 30 minutes was 30 μm. Using this substrate, an adhesion exposure test was carried out under the conditions of an ultraviolet illuminance of 400 mJ / cm ² and a vacuum drawing of 750 mmHg using HMW-20D manufactured by Oak Seisakusho.
A tape peeling test similar to the appearance observation and ethanol abrasion test of the pressure-sensitive adhesive tape for photomask protection, in which the adhesion exposure test was performed up to 500 times, was performed. Those having a small increase in peel strength compared to the initial value are good.

(3) Measurement of peeling force:
A Nitto Denko adhesive tape 31B was bonded to the surface protective layer side of the photomask protecting adhesive tape in accordance with JIS Z0237, and a peel test was conducted.

(4) Measurement of dynamic friction coefficient:
The dynamic friction coefficient was measured according to JIS K7125.

The evaluation results are shown in Table 1 or Table 2.
Moreover, among the results shown in Table 1, a graph showing the relationship between the blending ratio of methyl isocyanate and diol siloxane to the melamine resin in the surface protective layer, the dynamic friction coefficient, and the peeling force is shown in FIG.
Moreover, the graph which shows the relationship between the value of the surface layer / intermediate layer in a surface protective layer among the results shown in Table 2, a dynamic friction coefficient, and peeling force was shown in FIG.

From the evaluation results in Tables 1 and 2, the examples were compared with comparative examples that did not satisfy the invention specific matters.
“The surface protective layer (C), which is a specific matter of the present invention, contains isocyanate silane (x), siloxane (y) having a hydroxyl group at the terminal, and a melamine compound (z1) and / or a guanamine compound (z2). mixture Comparative example 3 which does not satisfy the requirements of the curing consists product "obtained from, there is a problem in transparency for the value of HAZE is high, Comparative example 3 or 4, the release force obtained from the contact exposure evaluation It has changed before and after the evaluation, and it can be seen that the durability is low.
Further, “the ratio of isocyanate silane (x) and siloxane (y) having a hydroxyl group at the terminal is a specific matter of the present invention with respect to 100 parts by weight of melamine compound (z1) and / or guanamine compound (z2). It is understood that Comparative Example 1 which does not satisfy the requirement of “0.5 to 30 parts by weight” has a heavy peeling force obtained from the ethanol resistance and adhesion exposure evaluation and has a low durability. Similarly, although Comparative Example 2 satisfies the conditions as a commonly used photomask protective adhesive tape, it is unsuitable as a photomask protective adhesive tape that "slidably reduces" due to its low coefficient of dynamic friction. I understand that.
Further, “surface layer (e), which is a specific matter of the present invention, comprises a cured product obtained from a mixture containing isocyanate silane (y) and siloxane (z) having a hydroxyl group at the terminal, and surface layer (e ) Is not more than 0.5% to 30% with respect to the thickness of the intermediate layer (d) ", Comparative Example 5, which does not satisfy the requirement, has poor durability in adhesion exposure evaluation and is peeled from the initial stage. It is unsuitable because it is heavy, and it can be seen that Comparative Example 6 has no problem with durability and transparency, but has a low coefficient of dynamic friction and is slippery.
Compared with these, the photomask protective adhesive tapes according to Examples 1 to 9 are a photomask having both HAZE (transparency), durability obtained from a contact exposure test, and slip resistance obtained from measurement of a dynamic friction coefficient. It was confirmed that it was a protective adhesive tape.
Also, even if the mixing ratio of isocyanate silane (x) and siloxane having a hydroxyl group (y) is the same in the two-layer coated product and the one-component mixed type, the numerical value such as the dynamic friction coefficient is different. This is probably because not all of the silicone layer appeared on the surface.

Claims (9)

Transparent base film or sheet (A), pressure-sensitive adhesive layer (B) formed on one side thereof, and surface protective layer (C) formed on the side opposite to the side of the pressure-sensitive adhesive layer (B) An adhesive tape for protecting a photomask including:
The surface protective layer (C) consists of a cured product obtained from a mixture containing the following (x), (y) and (z1) and / or (z2), and
In said mixture, (x) and the ratio of (y) is, (z1) and / or (z2) with respect to 100 parts by weight, the photomask protecting adhesive tape, characterized in that from 5 to 30 wt parts.
(X): Isocyanatosilane (y): Siloxane having a hydroxyl group at the terminal (z1): Melamine compound (z2): Guanamin compound Transparent base film or sheet (A), pressure-sensitive adhesive layer (B) formed on one side thereof, and surface protective layer (C) formed on the side opposite to the side of the pressure-sensitive adhesive layer (B) An adhesive tape for protecting a photomask including:
The surface protective layer (C) is composed of an intermediate layer (d) and a surface layer (e) that are sequentially formed on the surface opposite to the surface of the pressure-sensitive adhesive layer (B),
The intermediate layer (d) is composed of a cured product containing a melamine compound (z1) and / or a guanamine compound (z2),
The surface layer (e) is composed of a cured product obtained from a mixture containing the following (x) and (y), and
The thickness of the surface layer (e) is 0.5 to 30% with respect to the thickness of the intermediate layer (d).
(X): Isocyanatosilane (y): Siloxane having a hydroxyl group at the terminal   The adhesive tape for protecting a photomask according to claim 1 or 2, wherein the surface protective layer (C) has a coefficient of dynamic friction measured according to JIS K7125 of 0.1 to 0.4.   The pressure-sensitive adhesive tape for protecting a photomask according to any one of claims 1 to 3, wherein the isocyanate silane (x) is a tri- or tetrafunctional isocyanate silane.   The pressure-sensitive adhesive tape for protecting a photomask according to claim 4, wherein the tri- or tetrafunctional isocyanate silane is methyl triisocyanate silane or tetraisocyanate silane.   The pressure-sensitive adhesive tape for photomask protection according to any one of claims 1 to 5, wherein the siloxane (y) having a hydroxyl group at the terminal is a diol having two hydroxyl groups at the terminal.   The pressure-sensitive adhesive tape for photomask protection according to any one of claims 1 to 6, wherein the melamine compound (z1) is methylolmelamine or a derivative thereof.   The pressure-sensitive adhesive tape for protecting a photomask according to claim 7, wherein the methylol melamine is hexamethylol melamine.   The pressure-sensitive adhesive tape for photomask protection according to any one of claims 1 to 7, wherein the guanamine compound (z2) is benzoguanamine or a derivative thereof.

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